What is An Allergy

What is an Allergy?

Allergies are an abnormal response of the immune system. It is an acquired potential for developing adverse reactions that are immunologically mediated to the substances that are mostly harmless to us. This substance (pollen, mould, animal dander for example)is called an allergen.

The prevalence of asthma and rhinitis – two major forms of allergies – was one and 10 percent respectively in 1964 in the country. But, new data as per WAO (World Allergy Organization) shows that about 14 per cent people now have asthma, while over 20 per cent are suffering from allergic rhinitis (AR) which results from an IgE-mediated inflammation of the nasal mucosa. Currently, about 20 to 30 per cent of people in India are having one or more allergic diseases and their prevalence is rising dramatically, the WAO said.

How Allergy develops?

The Development of allergies involves IgE Antibodies. It is a two step process by which individual initially become sensitized to a substance.

During the early stage of sensitization, the individual develops significant amount of IgE antibodies against an inhaled, ingested or injected substance. Memory B cell also appear that are capable of immediately producing more of this specific antibodies when stimulated.

The second stage involves adherence of this newly formed IgE to circulating basophils or to the mast cell located in the skin, mucosal surfaces of gastrointestinal tract or respiratory system.

The new exposure simply added to the existing population so that there are millions of IgE molecule directed against different allergens, present on the surface of each mast cell and basophils.

This process of sensitization does not produce any symptoms that we equate with allergic disease.

The second step in the two step process of becoming allergic involves the re-exposure of a sensitized person to the same allergen. With exposure production symptoms may vary from mild for example sneezing to sudden death.

What Are the Symptoms of an Allergic Reaction?

Common symptoms of an allergic reaction to inhaled or skin allergens include:

Itchy, watery eyes

Sneezing

Itchy, runny nose

Rashes

Feeling tired or ill

Hives (a rash with raised red patches)

What are the types of Allergies?

Allergy related diseases can be classified based on the target organ involvement. Some common types are mentioned below.

Nose – allergic rhinitis

Lungs -Asthma

Skin -Dermatitis

Eye -Conjunctivitis

Systemic-Anaphylaxis

Gut -Food allergy

Ear –otitis media

What are the Risk factors for Allergy?

Family history of allergies

Serum IgE>100 IU/ml before age of 6 years

Animal contact

Dust mite exposure

Passive smoking

Eczema

Small family size

Early use of antibiotics

Western life style

diet

Genetics of Allergy

If one parent is atopic >= 50 % risk

If both parents are atopic >=66 % risk

No family history < 20%

*Exact mode of genetic transmission is still not known but the positive family history is the single most important factor to predict the development of allergies.

How Allergy is Diagnosed?

Thorough history should taken by an experienced physician. Also questionnaires are recommended for completeness.

Disclaimer : The information given in the website is for awareness purpose only. Patients are strictly advised not to self medicate by using the information regarding drugs mentioned in the website www.asthmallergyclinic.in . Self medication is dangerous & can even be fatal in extreme cases. Also due to latest research worldwide in Medical field, the information in the website, may not be updated in real time. Patients are advised to seek advice from an Allergist / Allergy specialist for the correct diagnosis & treatment.